U.S. patent number 6,517,303 [Application Number 09/082,484] was granted by the patent office on 2003-02-11 for substrate transfer shuttle.
This patent grant is currently assigned to Applied Komatsu Technology, Inc.. Invention is credited to David E. Berkstresser, Wendell T. Blonigan, Ernst Keller, Shinichi Kurita, Robin L. Tiner, Norman L. Turner, John M. White.
United States Patent |
6,517,303 |
White , et al. |
February 11, 2003 |
**Please see images for:
( Certificate of Correction ) ** |
Substrate transfer shuttle
Abstract
The present invention provides an apparatus and method for
substrate transport. In systems according to the invention, at
least a first and second chamber are provided. The first chamber
may be a load lock and the second chamber a processing chamber. A
substrate transfer shuttle is provided and is moveable along a
linear path defined by guide rollers between one position in the
first chamber and another position in the second chamber. In this
way, the substrate may be transferred, in both a forward and a
reverse direction, between the first chamber and the second
chamber. The substrate transfer shuttle is structured so that a
substrate may be removed therefrom by moving a support in one of
the chambers from a lowered position to an intermediate position,
after which the substrate transfer shuttle may be removed from the
chamber.
Inventors: |
White; John M. (Hayward,
CA), Turner; Norman L. (Vero Beach, FL), Tiner; Robin
L. (Santa Cruz, CA), Keller; Ernst (Sunnyvale, CA),
Kurita; Shinichi (San Jose, CA), Blonigan; Wendell T.
(Union City, CA), Berkstresser; David E. (Los Gatos,
CA) |
Assignee: |
Applied Komatsu Technology,
Inc. (Tokyo, JP)
|
Family
ID: |
22171518 |
Appl.
No.: |
09/082,484 |
Filed: |
May 20, 1998 |
Current U.S.
Class: |
414/217;
414/939 |
Current CPC
Class: |
C03B
29/08 (20130101); C03B 35/202 (20130101); H01L
21/67173 (20130101); F27D 3/00 (20130101); H01L
21/67236 (20130101); H01L 21/67748 (20130101); C03C
17/002 (20130101); F27D 5/00 (20130101); C03B
35/142 (20130101); C03B 25/08 (20130101); C03B
2225/02 (20130101); Y02P 40/57 (20151101); Y10S
414/135 (20130101); Y10S 414/139 (20130101) |
Current International
Class: |
C03B
35/20 (20060101); C03B 29/08 (20060101); C03B
25/08 (20060101); C03C 17/00 (20060101); C03B
35/00 (20060101); C03B 35/14 (20060101); C03B
29/00 (20060101); C03B 25/00 (20060101); F27D
3/00 (20060101); H01L 21/677 (20060101); F27D
5/00 (20060101); H01L 21/00 (20060101); H01L
21/67 (20060101); B65G 001/33 () |
Field of
Search: |
;414/217,217.1,939,941 |
References Cited
[Referenced By]
U.S. Patent Documents
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Other References
IBM Technical Disclosure Bulletin, vol. 17, No. 8, p. 2268-9, Jan.
1975, Y. Budo, R.D. Dreyer, A.C. Key, J.E. Kulak, B.E. MacKennie.
.
PCT International Search Report on Ser. No. PCT/US 99/11060, dated
May 13, 1999. .
PCT International Search Report on Ser. No. PCT/IB 99/10395, Sep.
29, 1999, 8 pages. .
PCT International Search Report on Ser. No. PCT/US 99/10687, Oct.
11, 1999. .
PCT International Search Report PCT/IB 99/01431 Dated Jul. 28,
2000..
|
Primary Examiner: Morse; Gregory A.
Attorney, Agent or Firm: Thomason, Moser & Patterson,
L.L.P.
Parent Case Text
RELATED APPLICATIONS
The present application is related to U.S. patent application Ser.
No. 08/946,922, entitled "MODULAR CLUSTER PROCESSING SYSTEM," filed
Oct. 8, 1997, now abandoned. The present application is also
related to the following U.S. patent applications which are being
filed concurrently with this application: (1) "Method and Apparatus
for Substrate Transfer and Processing," U.S. Ser. No. 09/082,428,
filed on May 20, 1998; (2) "Multi-Function Chamber For A Substrate
Processing System," now U.S. Pat. No. 6,086,362, issued on Jul. 11,
2000; (3) "An Automated Substrate Processing System," U.S. Ser. No.
09/082,413, filed on May 20, 1998; (4) "Substrate Transfer Shuttle
Having a Magnetic Drive," U.S. Ser. No. 09/082,605, filed on May
20, 1998 and; (5) "In-Situ Substrate Transfer Shuttle," U.S. Ser.
No. 09/082,488, filed on May 20, 1998.
The foregoing patent applications, which are assigned to the
assignee of the present application, are incorporated herein by
reference.
Claims
What is claimed is:
1. A system for processing a substrate, comprising: a first
chamber; a second chamber coupled to the first chamber and
configured to perform a process on the substrate; a valve to
selectively seal the first chamber from the second chamber when
closed and to permit transfer of the substrate between the first
chamber and the second chamber through the valve when open; a
substrate transfer shuttle moveable along a linear path, defined by
guide rollers, between one position in the first chamber and
another position in the second chamber to transfer the substrate
between the first chamber and the second chamber, and further
moveable along the linear path between the another position in the
second chamber and the one position in the first chamber to
transfer the substrate between the second chamber and the first
chamber, the shuttle having one or more substrate support fingers
disposed thereon; and a substrate support disposed in the second
chamber and adapted to move from a lower position to a higher
position, wherein at least a portion of the substrate support moves
between the substrate support fingers of the shuttle.
2. An apparatus for processing a substrate, comprising: a load lock
chamber for introduction of the substrate; a processing chamber
coupled to the load lock chamber and configured to perform a
process on the substrate, said processing chamber having a
susceptor for supporting the substrate during the process, the
susceptor movable between lowered, intermediate, and raised
positions, wherein the susceptor in the processing chamber includes
a plurality of lift pins which are movable through holes in the
susceptor and which support the substrate above the susceptor in
the intermediate and raised positions; a valve to selectively seal
the load lock chamber from the processing chamber when closed and
to permit transfer of the substrate between the load lock chamber
and the processing chamber through the valve when open; a substrate
transfer shuttle moveable along a shuttle path between one position
in the load lock chamber and another position in the processing
chamber to transfer the substrate between the load lock chamber and
the processing chamber, the substrate transfer shuttle configured
and arranged so that when in said another position, the substrate
may be removed from the substrate transfer shuttle by moving the
susceptor from the lowered position to the intermediate position,
after which the substrate transfer shuttle may be removed from the
processing chamber, the shuttle having one or more substrate
support fingers disposed thereon, wherein at least a portion of the
susceptor is adapted to move between the substrate support fingers
of the shuttle, wherein the substrate transfer shuttle includes:
first and second longitudinal side rails at respective first and
second sides thereof; a first plurality of the substrate support
elements extending inwardly from the first longitudinal side rail
and positioned to pass below the substrate when the substrate
transfer shuttle is removed from the processing chamber; and a
second plurality of the substrate support elements extending
inwardly from the second longitudinal side rail and positioned to
pass below the substrate when the substrate transfer shuttle is
removed from the processing chamber.
3. The apparatus of claim 2, wherein the lift pins are adjacent
respective ones of the substrate support elements.
4. The apparatus of claim 3, wherein said lift pins are nearer to a
centerline of the substrate than the pluralities of substrate
support elements.
5. The apparatus of claim 2, further including a plurality of pads
located on said pluralities of substrate support elements to
support the substrate above said substrate support elements.
6. The apparatus of claim 5, wherein said pads are sufficiently
high such that bowing of a heated substrate does not result in the
substrate directly contacting the substrate support elements.
7. The apparatus of claim 2, further comprising a plurality of
stoppers located on said pluralities of substrate support elements
to secure the substrate against lateral movement.
8. The apparatus of claim 2, further including a first cross member
structurally connecting the first and second longitudinal side
rails.
9. The apparatus of claim 8, further including a second
cross-member structurally connecting the first and second
longitudinal side rails and having an underside, the underside
positioned to pass over the susceptor when the substrate transfer
shuttle is introduced into or removed from the processing
chamber.
10. The apparatus of claim 9, wherein at least the first
longitudinal side rail has a portion extending beyond the second
cross-member and accommodated within an associated alcove in the
load lock chamber when the substrate transfer shuttle is in the one
position.
11. The apparatus of claim 6, wherein the second longitudinal side
rail has a portion extending beyond the second cross-member and
accommodated within an associated alcove in the load lock chamber
when the substrate transfer shuttle is in the one position.
12. The apparatus of claim 8, wherein the first cross-member has an
underside positioned to pass over the susceptor when the substrate
transfer shuttle is removed from the processing chamber.
13. The apparatus of claim 2, wherein said substrate support
elements extend about 15-30% of a dimension of the substrate.
14. The apparatus of claim 13, wherein said substrate support
elements extend about 22% of a dimension of the substrate.
15. The apparatus of claim 2, further including a first drive
mechanism engageable with at least the first longitudinal side rail
to move the substrate transfer shuttle along at least a first
portion of the shuttle path.
16. The apparatus of claim 15, further including a second drive
mechanism engageable with at least the first longitudinal side rail
to move the substrate transfer shuttle along at least a second
portion of the shuttle path.
17. The apparatus of claim 15, wherein the first longitudinal side
rail includes a mechanical drive element.
18. The apparatus of claim 17, wherein said mechanical drive
element is a toothed rack.
19. The apparatus of claim 15, wherein the first drive mechanism is
engageable with both the first and second longitudinal side
rails.
20. The apparatus of claim 2, wherein the substrate support
elements, extending inwardly from the first longitudinal side rail,
each have a proximal portion extending at least in part upwardly
from the first rail and have a distal portion extending inwardly
from the proximal portion so that when the substrate transfer
shuttle is supporting a substrate, an end effector may be
accommodated vertically between the substrate and the first
longitudinal side rail and laterally between at least some of the
substrate support elements extending inwardly from the first
longitudinal side rail.
21. The apparatus of claim 2, wherein the processing chamber
includes a susceptor support depending from the susceptor, the
susceptor support movable to raise and lower the susceptor and
wherein at least a group of the first and second pluralities of
substrate support elements are positioned to pass alongside the
susceptor support when the substrate transfer shuttle is withdrawn
along the shuttle path.
22. An apparatus for performing a process on a substrate,
comprising: a load lock chamber for introduction of the substrate;
a first processing chamber coupled to the load lock chamber and
configured to perform a process on the substrate, the first
processing chamber including a first susceptor to support the
substrate during performance of the process and the first susceptor
being movable between lowered, intermediate, and raised positions;
a valve to selective seal the load lock chamber from the first
processing chamber when closed and to permit transfer of the
substrate between the load lock chamber and the first processing
chamber when open; a substrate transfer shuttle supported on a
track by rails extending from the shuttle and moveable along a
linear shuttle path between one position in the load lock chamber
and a second position in the first processing chamber to transfer
the substrate between the load lock chamber and the first
processing chamber, the substrate transfer shuttle configured and
arranged so that when in said second position, the substrate may be
removed from the substrate transfer shuttle by moving at least a
portion of the susceptor from the lowered position to the
intermediate position, after which the substrate transfer shuttle
may be removed from the processing chamber; a second processing
chamber coupled to the first processing chamber and configured to
perform a process on the substrate, the second processing chamber
including a second susceptor to support the substrate during
performance of the process and the second susceptor being movable
between lowered, intermediate, and raised positions; a second valve
to selectively seal the second processing chamber from the first
processing chamber when closed and to permit transfer of the
substrate between the second processing chamber and the first
processing chamber when open; and wherein the substrate transfer
shuttle is further moveable along a linear shuttle path between the
second position and a third position in the second processing
chamber to transfer a substrate between the first processing
chamber and the second processing chamber, the substrate transfer
shuttle configured and arranged so that a substrate thereon in the
third position may be removed by moving the susceptor of the second
processing chamber from the lowered position to the intermediate
position, after which the substrate transfer shuttle may be
withdrawn from the second processing chamber.
23. An apparatus for performing a process on a substrate,
comprising: a first chamber having a mechanism to support the
substrate therein, the mechanism movable between retracted and
extended positions; a second chamber coupled to the first chamber;
a valve to selectively seal the first chamber from the second
chamber when closed and to permit transfer of the substrate through
the valve when open; a substrate transfer shuttle supported on a
track by rails extending from the shuttle and moveable along a
linear path which extends at least between one position in the
first chamber and another position in the second chamber to
transfer the substrate between the first chamber and the second
chamber, the substrate transfer shuttle configured and arranged so
that a substrate in the one position may be removed from the
substrate transfer shuttle by moving the support mechanism to the
extended position after which the substrate transfer shuttle may be
removed from the first chamber.
24. The apparatus of claim 23, wherein said second chamber further
includes a mechanism to support the substrate therein, the
mechanism movable between retracted and extended positions, so that
a substrate in the another position may be removed from the
substrate transfer shuttle by moving at least a portion of the
support mechanism to the extended position after which the
substrate transfer shuttle may be removed from the second
chamber.
25. An apparatus for performing a process on a substrate,
comprising: a first chamber having a mechanism to support the
substrate therein, the mechanism movable between retracted and
extended positions; a second chamber coupled to the first chamber
and having a mechanism to support the substrate therein, the
mechanism movable between retracted and extended positions; a first
valve to selectively seal the first chamber from the second chamber
when closed and to permit transfer of the substrate through the
first valve when open; a third chamber coupled to the second
chamber and having a mechanism to support the substrate therein,
the mechanism movable between retracted and extended positions; a
second valve to selectively seal the second chamber from the third
chamber when closed and to permit transfer of the substrate through
the second valve when open; two substrate transfer shuttles, each
moveable along a linear path which extends at least between one
position in the first chamber and another position in the third
chamber to transfer the substrate between the first chamber, the
second chamber, and the third chamber, one of the substrate
transfer shuttles to transfer substrates between the first chamber
and the second chamber, the other of the substrate transfer
shuttles to transfer substrates between the second chamber and the
third chamber, said substrate transfer shuttles configured and
arranged so that when in a selected one of the chambers, the
substrate may be removed from the substrate transfer shuttle by
moving the support mechanism to the extended position after which
the substrate transfer shuttle may be removed from the selected one
of the chambers; the shuttles each having one or more substrate
support fingers disposed thereon, at least a portion of one or more
of the mechanisms disposed in the chambers being adapted to move
between the substrate support fingers of the shuttle.
26. An apparatus for performing a process on a substrate,
comprising: a first load lock chamber; a first load lock valve to
selectively seal the first load lock chamber from the first chamber
when closed and to permit transfer of the substrate through the
first load lock valve when open; a first chamber coupled to said
first load lock chamber and having a mechanism to support the
substrate therein, the mechanism movable between retracted and
extended positions; a second chamber coupled to the first chamber
and having a mechanism to support the substrate therein, the
mechanism movable between retracted and extended positions; a first
valve to selectively seal the first chamber from the second chamber
when closed and to permit transfer of the substrate through the
first valve when open; a third chamber coupled to the second
chamber and having a mechanism to support the substrate therein,
the mechanism movable between retracted and extended positions; a
second valve to selectively seal the second chamber from the third
chamber when closed and to permit transfer of the substrate through
the second valve when open; a second load lock chamber; a second
load lock valve to selectively seal the second load lock chamber
from the third chamber when closed and to permit transfer of the
substrate through the second load lock valve when open; two
substrate transfer shuttles, each shuttle supported on a track by
rails extending from the shuttle and moveable along a linear path
which extends at least between one position in the first load lock
chamber and another position in the second load lock chamber to
transfer the substrate between the first load lock chamber, the
first chamber, the second chamber, the third chamber, and the
second load lock chamber, one of the substrate transfer shuttles to
transfer substrates between the first load lock chamber, the first
chamber and the second chamber, the other of the substrate transfer
shuttles to transfer substrates between the second chamber, the
third chamber and the second load lock chamber, said substrate
transfer shuttles configured and arranged so that when in a
selected one of the chambers, the substrate may be removed from the
substrate transfer shuttle by moving the support mechanism from the
retracted position to the extended position after which the
substrate transfer shuttle may be removed from the selected one of
the chambers.
27. An apparatus for processing a substrate, comprising: a first
load lock chamber for introduction of the substrate; a second load
lock chamber for removal of the substrate; at least one
intermediate chamber located between the first and second load lock
chambers, said intermediate chamber configured to perform a process
on a substrate; a first valve to selectively seal the first load
lock chamber from the intermediate chamber; a second valve to
selectively seal the second load lock chamber from the intermediate
chamber; a substrate transfer shuttle supported on a track by rails
extending from the shuttle and moveable along a linear path defined
by guide rollers between one position external to the intermediate
chamber and another position in the intermediate chamber to
transfer a substrate to the intermediate chamber, the substrate
transfer shuttle configured and arranged so that a substrate in the
intermediate chamber may be removed from the substrate transfer
shuttle after which the substrate transfer shuttle may be removed
from the intermediate chamber.
28. The apparatus of claim 27, further including a plurality of
intermediate chambers located between the first load lock chamber
and the second load lock chamber.
29. The apparatus of claim 28, further including two substrate
transfer shuttles, a first one of said substrate transfer shuttles
moveable along a first shuttle path between the first load lock
chamber and the intermediate chamber and a second one of said
substrate transfer shuttles moveable along a second shuttle path
between the second load lock chamber and the intermediate
chamber.
30. A system for processing a substrate, comprising: a first
chamber; a second chamber coupled to the first chamber and
configured to perform a process on a substrate; a valve to
selectively seal the first chamber from the second chamber when
closed and to permit transfer of the substrate between the first
chamber and the second chamber through the valve when open; a
support mechanism disposed in at least one of the chambers and
movable between retracted and extended positions; a substrate
transfer shuttle supported on a track by rails extending from the
shuttle and moveable along a linear path between one position in
the first chamber and another position in the second chamber to
transfer the substrate between the first chamber and the second
chamber; the substrate transfer shuttle configured and arranged so
that a substrate may be removed from the substrate transfer shuttle
by moving at least a portion of the support mechanism to the
extended position after which the substrate transfer shuttle may be
removed from the respective chamber; and a drive mechanism
engageable with the substrate transfer shuttle to move the
substrate transfer shuttle along at least a portion of the linear
path.
31. A substrate transfer shuttle for carrying a substrate in a
processing system having at least two chambers, the shuttle
comprising: a) first and second longitudinal side rails; b) cross
members proximate first and second ends of the first and second
longitudinal side rails to structurally connect the first and
second longitudinal side rails; c) a first plurality of substrate
support elements extending inwardly from the first longitudinal
side rail; and d) a second plurality of substrate support elements
extending inwardly from the second longitudinal side rail; wherein
the shuttle has one or more substrate support finders disposed
thereon, the substrate transfer shuttle being moveable along a
shuttle path between one position in a load lock chamber of the
processing system and another position in a processing chamber of
the processing system to transfer the substrate between the load
lock chamber and the processing chamber, the substrate transfer
shuttle configured and arranged so that when in said another
position, the substrate may be removed from the substrate transfer
shuttle by moving at least a portion of a susceptor from a lowered
position to an intermediate position between the substrate support
fingers of the shuttle, after which the substrate transfer shuttle
may be removed from the processing chamber.
32. The apparatus of claim 31, wherein said substrate support
elements extend about 15-30% of a dimension of the substrate.
33. The apparatus of claim 32, wherein said substrate support
elements extend about 22% of a dimension of the substrate.
34. The apparatus of claim 31, wherein the first and second
longitudinal side rails each include a toothed rack mounted on the
underside thereof.
35. The apparatus of claim 31, wherein the substrate support
elements, extending inwardly from the first and second longitudinal
side rails, each have a proximal portion extending at least in part
upwardly from the first longitudinal side rails and a distal
portion extending horizontally inwardly from the proximal portion
so that when the substrate transfer shuttle is supporting a
substrate, an end effector may be accommodated vertically between
the substrate and the first longitudinal side rail and laterally
between at least some of the proximal portions of the substrate
support elements.
36. The apparatus of claim 31, wherein at least the first
longitudinal side rail has a portion extending beyond the second
cross-member.
37. The apparatus of claim 31, wherein the distal portions of the
substrate support elements are parallel.
38. The apparatus of claim 31, wherein at least one of the distal
portions of the substrate support elements is at an angle with
respect to at least another of the distal portions of the substrate
support elements.
Description
BACKGROUND
The invention relates to substrate processing, and more
particularly to transferring substrates to and from processing
chambers.
Glass substrates are being used for applications such as active
matrix televisions and computer displays, among others. A large
glass substrate can form multiple display monitors, each of which
may contain more than a million thin film transistors.
The processing of large glass substrates often involves the
performance of multiple sequential steps, including, for example,
the performance of chemical vapor deposition (CVD) processes,
physical vapor deposition (PVD) processes, or etch processes.
Systems for processing glass substrates can include one or more
process chambers for performing those processes.
The glass substrates can have dimensions, for example, of 550 mm by
650 mm. The trend is toward even larger substrate sizes, such as
650 mm by 830 mm and larger, to allow more displays to be formed on
the substrate or to allow larger displays to be produced. The
larger sizes place even greater demands on the capabilities of the
processing systems.
Some of the basic processing techniques for depositing thin films
on the large glass substrates are generally similar to those used,
for example, in the processing of semiconductor wafers. Despite
some of the similarities, however, a number of difficulties have
been encountered in the processing of large glass substrates that
cannot be overcome in a practical way and cost effectively by using
techniques currently employed for semiconductor wafers and smaller
glass substrates.
For example, efficient production line processing requires rapid
movement of the glass substrates from one work station to another,
and between vacuum environments and atmospheric environments. The
large size and shape of the glass substrates makes it difficult to
transfer them from one position in the processing system to
another. As a result, cluster tools suitable for vacuum processing
of semiconductor wafers and smaller glass substrates, such as
substrates up to 550 mm by 650 mm, are not well suited for the
similar processing of larger glass substrates, such as 650 mm by
830 mm and above. Moreover, cluster tools require a relatively
large floor space.
One way to improve such processing tools is disclosed in U.S.
patent application Ser. No. 08/946,922, entitled "MODULAR CLUSTER
PROCESSING SYSTEM," assigned to Applied Komatsu Technologies, Inc.
of Santa Clara, Calif., and incorporated above by reference. The
use of a modular processing system is disclosed, with substrate
movement exterior of processing islands performed by conveyors or
robots on tracks. Substrate movement interior of processing islands
is performed by a substrate transporter. In this type of system,
the transporter may move a substrate into or out of a processing
chamber, after which the transporter may stay resident in either
load lock.
Similarly, chamber configurations designed for the processing of
relatively small semiconductor wafers are not particularly suited
for the processing of these larger glass substrates. The chambers
must include apertures of sufficient size to permit the large
substrates to enter or exit the chamber. Moreover, processing
substrates in the process chambers typically must be performed in a
vacuum or under low pressure. Movement of glass substrates between
processing chambers, thus, requires the use of valve mechanisms
which are capable of closing the especially wide apertures to
provide vacuum-tight seals and which also must minimize
contamination.
Furthermore, relatively few defects can cause an entire monitor
formed on the substrate to be rejected. Therefore, reducing the
occurrence of defects in the glass substrate when it is transferred
from one position to another is critical. Similarly, misalignment
of the substrate as it is transferred and positioned within the
processing system can cause the process uniformity to be
compromised to the extent that one edge of the glass substrate is
electrically non-functional once the glass has been formed into a
display. If the misalignment is severe enough, it even may cause
the substrate to strike structures and break inside the vacuum
chamber.
Other problems associated with the processing of large glass
substrates arise due to their unique thermal properties. For
example, the relatively low thermal conductivity of glass makes it
more difficult to heat or cool the substrate uniformly. In
particular, thermal losses near the edges of any large-area, thin
substrate tend to be greater than near the center of the substrate,
resulting in a non-uniform temperature gradient across the
substrate. The thermal properties of the glass substrate combined
with its size, therefore, makes it more difficult to obtain uniform
characteristics for the electronic components formed on different
portions of the surface of a processed substrate. Moreover, heating
or cooling the substrates quickly and uniformly is more difficult
as a consequence of its poor thermal conductivity, thereby reducing
the ability of the system to achieve a high throughput.
As noted above, efficient production line processing requires rapid
movement of the glass substrates from one work station to another.
Other requirements include a structure that can firmly support the
glass substrate during transfer and that can transport the glass
substrate to all areas of a work station or processing island.
SUMMARY
The present invention allows large glass substrates to be moved
within a processing station and from one processing station to
another. In systems according to the invention, at least a first
and second chamber are provided. Typically, the first chamber is a
load lock and the second chamber is a processing chamber. The
processing chamber may serve as an inspection station, a CVD
chamber, a PECVD chamber, a PVD chamber, a post-anneal chamber, a
cleaning chamber, a descumming chamber, an etch chamber, or a
combination of such chambers. The load lock may be employed to heat
or cool the substrate. Two load locks may be employed, one to
perform heating and the other to perform cooling. The load locks
each include a platen for supporting the substrate.
A substrate transfer shuttle is used to move substrate along a
guide path defined by, e.g., guide rollers.
The substrate transfer shuttle is moveable along a linear path
defined by guide rollers between one position in the first chamber
and another position in the second chamber. In this way, the
substrate may be transferred, in both a forward and a reverse
direction, between the first chamber and the second chamber. The
substrate transfer shuttle is structured so that a substrate may be
removed therefrom by moving the platen from a lowered position to
an intermediate position, after which the substrate transfer
shuttle may be removed from the processing chamber. The substrate
transfer shuttle includes first and second longitudinal side rails
at respective first and second sides thereof. The shuttle also
includes first and second pluralities of substrate support elements
extending inwardly from the first longitudinal side rail and
positioned to pass below the substrate when the substrate transfer
shuttle is removed from the processing chamber. The substrate
support elements extend about 15-30% of a dimension of the
substrate, and more particularly about 22% of the width of the
substrate. Drive mechanisms are employed that engage with at least
the first longitudinal side rail to move the substrate transfer
shuttle along at least portions of the shuttle path.
Implementations of the invention may include one or more of the
following. A valve may be employed to selectively seal the first
chamber from the second chamber when closed and to permit transfer
of the substrate between the first chamber and the second chamber
through the valve when open. Multiple shuttles may be employed for
convenience in a particular process. Further, multiple intermediate
chambers may be located between the first and second chambers.
The susceptor in the processing chamber includes a plurality of
lift pins which are movable through holes in the susceptor and
which support the substrate above the susceptor.
Steps of the method include positioning a substrate onto a
substrate transfer shuttle in a load lock, and moving the substrate
transfer shuttle from the load lock into a processing chamber along
a first portion of a path. The substrate is removed from the
substrate transfer shuttle and positioned it on a platen in the
processing chamber. The substrate transfer shuttle is then removed
from the processing chamber and the substrate is processed.
Following processing, the substrate transfer shuttle is moved into
the processing chamber and the substrate is positioned thereon. The
substrate transfer shuttle and the substrate are moved into the
load lock, and the substrate is removed from the substrate transfer
shuttle.
Advantages of the invention include one or more of the following.
The invention eliminates unnecessary substrate movement in a
semiconductor processing system. For example, the substrate may be
transferred horizontally except for loading and unloading on the
susceptor. The invention also eliminates more expensive and
cumbersome vacuum robots and transfer chamber systems. The
invention allows removal of a substrate transfer shuttle during
processing, reducing contamination.
The details of one or more embodiments of the invention are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages of the invention will be apparent
from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan schematic view of a processing island of a
system according to the present invention.
FIG. 1A is a side schematic view of a section of a load lock
emptying alcoves.
FIGS. 2A-2C are top plan views of a shuttle and lifting fork
according to the present invention.
FIG. 2D is a side view showing a heated bowing glass substrate
supported on support fingers.
FIG. 3 is a side schematic view of a processing island of a system
according to the present invention.
FIG. 4 is a perspective view of a substrate transfer shuttle
according to the present invention.
FIG. 5 is a partial cross-sectional view of a processing chamber
and substrate transfer shuttle according to the present
invention.
FIG. 6A is a transverse cross-sectional view of a processing island
and shuttle according to an embodiment of the present
invention.
FIG. 6B is a transverse cross-sectional view of a processing island
and shuttle according to an alternative embodiment of the present
invention.
FIGS. 7A-7C are partial schematic cross-sectional views of a load
lock chamber according to the present invention, showing a
substrate in various stages of transfer from without to within a
load lock chamber.
FIGS. 7D and 7E are perspective views of alternative embodiments of
a substrate transfer shuttle and a platen as may be located in a
load lock chamber.
FIGS. 8A-8B are schematic cross-sectional views of a chamber
according to the present invention, shown in different stages of
transfer of a substrate between a shuttle and a susceptor in a
processing chamber.
Like reference numbers and designations in the various drawings
indicate like elements.
DETAILED DESCRIPTION
FIG. 1 shows a processing island 42 of a fabrication system
according to an embodiment of the present invention. Arrow 101
defines a direction pointing from "upstream" to "downstream" in the
processing island. The island 42 includes a substrate heating load
lock chamber 50 at a first end of the island and a substrate
cooling load lock chamber 52 at a second end of the island,
longitudinally opposite and downstream of the first end. Of course,
the terms "heating" and "cooling" are not intended to be limiting.
Rather, they are descriptive of exemplary features such chambers
may possess.
Between the load lock chambers 50 and 52 are a plurality of
processing chambers 54A-54C, which are connected in series between
the load lock chambers. Each processing chamber 54A-54C includes
first and second gate valves 56A-56C and 58A-58C, respectively, at
the first and second ends of each processing chamber (see also FIG.
3). The valve 56A selectively seals the load lock chamber 50 from
the processing chamber 54A when closed and permits transfer of
substrates through the valve between the load lock chamber 50 and
the processing chamber 54A when open. Similarly, the valve 58C
selectively seals the load lock chamber 52 from the processing
chamber 54C in a closed condition and permits the transfer of
substrates through the valve in an open condition. The valves 58A
and 56B seal the first processing chamber 54A from the second
processing chamber 54B when closed and permit the transfer of
substrates through the valves when open. Likewise, the valves 58B
and 56C selectively seal the second processing chamber 54B from the
third processing chamber 54C in closed conditions and permit the
transfer of substrates through the valves in open conditions. The
pairs of valves 58A, 56B and 58B, 56C may be replaced with single
valves although the illustrated configuration has advantages
described below. An example of the type of valve which may be
employed is described in above-mentioned U.S. patent application
entitled "Isolation Valves", U.S. Ser. No. 09/082,376, filed on May
20, 1998, and incorporated by reference above.
This detailed description describes an embodiment in which a glass
substrate is used. The term "substrate" is intended to broadly
cover any object that is being processed in a process chamber,
including flat panel displays, glass or ceramic plates, plastic
sheets, or disks. The present invention is particularly applicable
to large substrates such as glass plates having dimensions of 650
mm by 830 mm or even larger.
In this system, the substrate is supported by support fingers. The
support fingers may all be parallel, as shown in the embodiment of
FIGS. 1, 4 and 7D, or some may be angled as shown in the preferred
embodiment of FIGS. 2B-2C and 7E. In the described embodiments, the
short dimension of the substrate is generally parallel to the
direction of movement within a processing island.
FIGS. 1 and 3 show a substrate transfer shuttle in each of the load
locks 50 and 52. As shown in FIG. 3, the load lock chambers 50 and
52 have respective gate or slit valves 60 and 62 positioned along
one side of the island. The valves 60 and 62 (FIG. 3) selectively
seal their associated load lock chambers from atmosphere in closed
conditions and allow introduction or removal of substrates to or
from the load lock chambers in open conditions. In this figure,
valves 56A, 58A, 56B and 58B are shown open, and valves 56C and 58C
are shown closed.
The substrates may be introduced through the valve 60 to the load
lock chamber 50 which forms an entrance load lock chamber. With the
load lock chamber 50 in a condition sealed from the atmosphere and
process chamber 54A, the load lock chamber may be pumped to vacuum
and the substrate heated.
The load lock system allows a staged vacuum to occur. That is, the
process chamber vacuum need not be breached for substrates to be
loaded and unloaded. Since the load locks are independently
pumped-down prior to the opening of the valves separating them from
the process chambers, the process chamber pumps need only evacuate
a chamber that is already partially at vacuum. That is, they need
only maintain process vacuum conditions. Such a capability is
particularly important for, e.g., physical vapor deposition (PVD),
which may often require the lowest pressure of any process.
Each load lock chamber may be multifunctional. Process steps such
as heating, cooling, and descumming may be provided for in each
load lock. Heating and cooling may be provided for by heating and
cooling plates which may be moved into and out of thermal contact
with the substrate. Typically, the load lock 50 may be used to heat
and descum, while the load lock 52 may be used to cool. Ashing
processes may also be provided for in the chambers. The substrate
is then passed among the processing chambers 54A-54C. In each
processing chamber, a specific semiconductor process may be
performed on the substrate. Ashing or descumming may also occur in
a processing chamber. More details of a multifunctional load lock
may be found in above-mentioned U.S. patent application entitled
"Multi-Function Chamber for a Substrate Processing System," now
U.S. Pat. No. 6,086,362, issued on Jul. 11, 2000, and incorporated
by reference above.
A processed substrate may be cooled in the cooling load lock
chamber 52, which forms an exit load lock chamber, and may also be
brought up to atmospheric pressure. Thereafter, the substrate may
be removed from the system through the valve 62. Introduction and
removal of substrates to and from the load lock chambers 50 and 52
may be performed by robots 64A and 64B, respectively (see FIG. 1).
Alternatively, just one robot may be employed, operating on a track
or conveyor, to introduce or remove substrates.
Each robot includes an end effector in the form of a lifting fork
66A, 66B at the distal end of an arm 68A, 68B. At its proximal end,
each arm 68A, 68B is coupled to an associated vertical linear
actuator (not shown) to permit the arm and lifting fork to be
raised and lowered. Referring to FIGS. 2A and 2C, the top of the
lifting forks 66A and 66B may have thereon a number of supports 154
to support a substrate 126 on top of the fork 66A, 66B.
The robot 64A, for instance, can retrieve and return substrates to
and from substrate holding cassettes. In a first loading position,
the robot 64A may load a substrate into heating load lock chamber
50 of the island through the gate or slit valve 60 (FIG. 3). Robot
64B operates in a similar fashion to robot 64A. In a first or
lowered position, the fork 66A may be inserted beneath a substrate
in a cassette or on a shuttle in a load lock chamber. The fork
design is such that the same fork may be used for either,
facilitating considerable advantage in incorporating the system
into existing product lines. When raised to an intermediate
position, the upper surface of the fork 66A or, more particularly,
supports 154 (see FIGS. 2A and 2C) along the upper surface of the
fork tines, engage the lower surface of the substrate. When further
elevated to a second or raised position, the fork 66A lifts the
substrate out of engagement with the cassette or shuttle.
During loading, a z-rotary actuator of the robot 64A is caused to
rotate the loading end effector 66A 180.degree. so that the
substrate may be introduced into load lock heating chamber 50
through the slit valve 60. Fine adjustments may be made by the
z-linear actuator to adjust the height of the substrate so that the
substrate may enter through the slit valve 60 (FIG. 3) unimpeded.
During substrate loading, the slit valve 60 is opened and the
substrate is moved by a y-linear actuator in the y-direction. This
movement loads the substrate into load lock heating chamber 50
where it is lowered onto the shuttle 70 using the z-linear
actuator. The empty end effector 66A may then be withdrawn from the
chamber. Slit valve 60 is then closed and the heating and
evacuation process begun.
Associated with each load lock chamber 50 and 52 is a transfer
shuttle 70 and 72, respectively, configured for transporting
substrates between chambers. The first and second shuttles 70 and
72 are positioned in the heating and cooling load lock chambers
during introduction of a substrate to the heating load lock chamber
50 and removal of a substrate from the cooling load lock chamber
52, respectively. Transfer shuttles 70 and 72 may be made of
stainless steel, invar, ceramics or any other similar material.
Invar may be preferable as it has a low coefficient of thermal
expansion.
The load lock chambers 50 and 52 may be equipped with maintenance
windows or slits 152 (FIG. 1). These windows 152 allow the removal
of the components from the load locks for maintenance or repair.
During such a maintenance situation, both shuttle and chamber
components may be repaired.
Referring to FIGS. 1, 2B, 4, and 7D-7E, each shuttle 70, 72 has a
first end 31A facing from the associated load lock chamber toward
the adjacent processing chamber and a second end 31B opposite the
first end. Each shuttle further has first and second sides 32A and
32B, respectively. The shuttles may be mirror images of each other
and are positioned facing each other.
Referring specifically to FIG. 4, each shuttle includes first and
second side rails 74A and 74B along the respective first and second
sides of the shuttle. Both side rails extend substantially between
the first and second ends of the shuttle. The side rails are
parallel to and spaced-apart from each other. Each side rail
includes a generally flat horizontal strip 75. Along an outboard
portion of the underside of each strip, the rail bears a rack 76.
An outboard portion 77 of the underside of each rack bears angled
teeth 33 (the shape of the teeth are not shown). An inboard portion
78 of the underside of each rack is flat for engaging a number of
guide rollers as described below. First and second cross-members
80A and 80B, respectively, proximate the first and second ends of
the shuttle, structurally connect the first and second side rails
to each other. Each cross-member is slightly recessed from the
associated end of the shuttle, and each cross-member includes a
flat central horizontally-extending strip 82. First (83A and 84A)
and second (83B and 84B) legs depend from first and second ends of
the strip and connect such ends to the first and second side rails,
respectively.
An "X" indicates the location of the center of the substrate. This
X location should roughly correspond with the center of the
processing chamber, as measured in a horizontal plane, for optimum
processing of the substrate.
Substrate support fingers 86A, 88A, 86B and 88B extend inwardly
from the associated first and second side rails, respectively.
Referring to FIGS. 4 and 5, each support finger has a proximal
portion 90 extending upwardly from the associated side rail 75 and
a distal portion 92 extending horizontally inwardly from the
proximal portion and ending at a tip. At the tip, the upper surface
of each finger bears a pad 94 for supporting a substrate held by
the shuttle. As the shuttle must endure the temperatures used for
heating substrates, to temperatures of about 460.degree. C. or even
higher, the pads 94 may advantageously be made of a material such
as a ceramic, stainless steel, quartz, or other such materials. It
should be noted, however, that the temperature requirements of the
substrate transfer shuttle components may be lower than in prior
systems. In many prior systems, such as cluster tools, substrates
would be removed from a heating chamber by a vacuum robot which
would then transport the substrate to a processing chamber,
resulting in cooling of the substrate. A solution was to overheat
the substrate, intending for it to cool when transported.
In the present invention, the substrate transfer shuttle 70 moves
the substrate into a processing chamber directly from the heating
chamber. Thus, the requirement for overheating the substrate is
alleviated if not eliminated.
FIG. 5 also shows inner and outer chamber walls 38B and 38A,
respectively. A slot 38C is located in inner wall 38B to allow the
flat rail 75 of the shuttle to extend into the opening in wall 38B
to engage rollers 98. In this way, contamination caused by guide
rollers 98 may be minimized. Further, the process performed within
the chamber is kept separate from the mechanical components causing
the shuttle movement.
The width of the lifting forks 66A, 66B may be close to but less
than the distance between the two exterior support fingers 88A and
88B along one side of the shuttle 70. The central cut-out section
of the fork should be large enough such that it does not interfere
with the central support finger 86A. In the embodiment of FIGS.
2B-2C and 7E, where diagonal support fingers are employed, the
width of the fork may be larger.
In the illustrated preferred embodiment of FIGS. 2B-2C and 7E,
there are three support fingers associated with each side rail: a
central support finger 86A, 86B and two lateral diagonal support
fingers 88A, 88B. Each support finger preferably extends about
15-30% of a dimension such as the length or the diagonal of the
substrate in order to adequately support the substrate, and even
more preferably about 22% of the length approximately (0.22 l) of
the substrate. Referring to FIG. 2D, such placement ensures that
when a substrate 126 is heated, bowing caused by the substrate
flexibility results in a minimal volume swept out by the bowing
substrate as it moves along the flow path. In particular, by
constructing the fingers 86A, 86B, 88A, and 88B and pads 94 in this
configuration, where the pads are located at about the 22% point, a
minimal volume is swept out by the bowing substrate as it is moved
from one processing chamber to another, or between a processing
chamber and a load lock. Thus, the chance of such a substrate
striking, e.g., a platen or a susceptor, is substantially reduced.
This consideration is particularly important for glass substrates
on which TFT's are formed for flat panel displays, as these may be
only about 0.7-1 mm thick.
The height of pads 94 is also important. The height should be
chosen such that when the heated substrate bows, the edges of the
substrate do not make contact with the fingers directly. The
importance of this aspect to the quality of the resulting substrate
depends on the process requirements.
Another advantage of such a configuration is that the same support
fingers may be used to support several different sizes of
substrates. Moreover, the location of the support fingers is
adjustable to accommodate various substrate sizes. The location of
the pads 94 is also variable to accommodate different substrate
sizes. It should also be noted that while a shuttle servicing the
load lock chamber 50 must be designed to withstand high
temperatures, the shuttle servicing load lock chamber 52 has
somewhat more forgiving requirements, as it is less inclined to see
the maximum processing temperatures.
FIGS. 1, 4, and 7D show an alternate embodiment in which lateral
support fingers 88A and 88B are not diagonal but rather are
parallel to support fingers 86A and 86B. Other angled fingers may
be used, so long as they adequately support the substrate.
The above designs allow each shuttle to accept substrates from two
directions, each 90.degree. away from each other. First, the
shuttle may accept and release substrates in a direction
perpendicular to the side rails. Second, the shuttle may accept and
release substrates in a direction parallel to the side rails. In
any of the embodiments, a plurality of stoppers 201 may be
provided, as shown in FIGS. 2B-2C, 4-5 and 8A-8B, to ensure
accurate placement of the substrate on the support fingers and to
prevent accidental shifting of the substrate on the shuttle during
transport. Substrates may also be centered on the fingers by using
the plurality of stoppers 201. These stoppers 201 may have the
general shape of an inverted truncated cone, such as an inverted
frustum.
Along each side of the island (FIGS. 1, 3, 5, and 7A-7C), each load
lock chamber and each processing chamber includes a number of pairs
of guide rollers 98 (e.g., two rollers per side of the processing
chambers and three rollers per side of the load locks) positioned
so as to provide support and guidance to one or both shuttle(s) as
such shuttle(s) pass through the chambers. The guide rollers 98 may
be Teflon.RTM.-coated aluminum, Vespel.RTM., or any other such
material that is not particulate-generating and is soft for
dampening vibrations. Alternatively, suspensions may be employed to
provide a smooth movement. The guide rollers are all at
substantially even level and define a fixed path along which the
shuttles may move back and forth. The guide rollers are configured
to engage the flat inboard portion 78 of the underside of each rack
as a shuttle passes over the guide rollers so as to position and
orient the shuttle and provide smooth shuttle movement along the
predefined path.
As shown in FIG. 3, between each of the processing chambers 54A-54C
and the load lock chambers are chamber isolation valves whose
housings may each include a shuttle drive mechanism 100. Such a
configuration reduces particulate contamination within the
processing chambers as is often required, e.g., in TFT formation.
Such an island layout also facilitates a high degree of modularity
because each chamber has a similar structure and is
interchangeable. With one drive mechanism within the housing of
each isolation valve, the length of the shuttles used is generally
longer, as described in more detail below, than the associated
distance between the driving mechanisms. Moreover, the overall
length of the shuttles used is generally longer than the length of
any process chambers through which they pass.
As shown in FIG. 6A, each drive mechanism 100 includes a motor 102
external to the interior cavity of the associated chamber and
coupled to a drive shaft assembly 104 extending into and within the
interior of the load lock or valve housing. The inner chamber wall
38B is not shown for clarity. The drive shaft assembly 104 may
employ vacuum-compatible rotary feedthroughs. The drive shaft
assembly carries first and second pinion gears 106A and 106B
adjacent first and second sides of the associated chamber, and
first and second guide rollers 108A and 108B immediately inboard of
the first and second pinion gears, respectively. The pinion gears
are configured to mesh with the toothed outboard portions 33 of the
racks while the guide rollers are configured to contact the smooth
surface of the inboard portion of the racks of a shuttle passing
over the drive mechanism (see also FIGS. 4 and 5). Optionally, the
drive mechanism 100 includes an encoder 110 which provides input to
a control system 111 responsive to rotation of the associated drive
shaft assembly. The control system 111 may be connected to any and
each of the various chambers for controlling their operations as
well as the operation of any handling or processing equipment
external to the island. The control system may comprise a
user-programmable computer or other controller incorporating
appropriate software or firmware.
FIG. 6B shows an alternate configuration in which no drive shaft is
employed. In this configuration, the shuttle is driven from one
side only, and the motor may drive a pinion gear 106 without using
the drive shaft assembly 104. Laterally positioned guide rollers
203 may be used in addition to guide roller 108A and 108B to ensure
that the shuttle moves in a straight horizontal direction and is
not caused to misalign due to its only being driven on one side.
Rollers 203 are positioned on each side of a guide rail 112 in
order to keep the shuttle 70 moving in a straight and controlled
direction.
In either of these embodiments, it should be noted that it is not
crucial that the guide rollers be inboard of the pinion gears. In
fact, in an alternative embodiment, the guide rollers may be
outboard of the pinion gears or the relative position may be
different on each side of a line of chambers. In yet another
embodiment, rollers may be placed on the substrate transfer shuttle
and a smooth flat ridge may be located along each side of a line of
chambers to support the shuttle guide rollers.
In the following discussion, the placement of a substrate into a
load lock chamber is described with respect to FIGS. 7A-7E. In the
discussion of FIGS. 7A-7E, the support on which the substrate is
placed is referred to as a platen. The platen has slots through
which fingers of the shuttle may move when transferring substrates.
The placement of a substrate into a process chamber from a load
lock chamber is described with respect to FIGS. 8A-8B. In the
discussion of FIGS. 8A-8B, the support on which the substrate is
placed is referred to as a susceptor. The susceptor has passages
with extendable "T"-shaped pins for use in transferring substrates,
as described below. It should be noted that the above definitions
for platen and susceptor are used herein for clarity. The susceptor
in the processing chamber may be equally well termed a "platen" and
the platen in the load lock may be equally well termed a
"susceptor."
As shown in FIGS. 7A-7C, each load lock chamber 50, 52 (only
chamber 50 is shown) includes a platen 120 for supporting a
substrate during heating or cooling prior to or after processing. A
pedestal 122 supports the platen 120 and is raisable and lowerable
to raise and lower the platen 120 between a first or retracted
position and a second or extended position. The platen 120 is
generally rectangular and slightly larger than the plan area of the
substrate and has a plurality of channels 124 (FIGS. 7D and 7E)
extending inwardly from the opposite sides of the platen. The
channels are configured so as to accommodate the fingers 86A, 86B,
88A, and 88B of a shuttle 70 when the platen 120 is raised or
lowered through such a shuttle 70 as described below.
Initially, the load lock chamber 50 is vacant and is shielded from
the adjacent chamber 54A by the valve 56A. The load lock chamber 50
is vented to atmosphere and its slit valve 60 is opened to permit
introduction of a substrate to the island. As shown in FIG. 7A, a
substrate 126 is loaded into the load lock chamber 50 by the robot
end effector 66A. The end effector and substrate are inserted via a
horizontal (y-direction) movement into the chamber 50 at a height
at which the underside of the end effector 66A is above the fingers
88A, 88B of the shuttle 70. The end effector 66A carrying the
substrate 126 is stopped with the substrate 126 located centrally
above the platen and then lowered. Eventually, the end effector 66A
reaches a second height shown in FIG. 7B. During movement between
the first height and the second height, the end effector passes
below the fingers of the shuttle, with e.g., one tine of the end
effector 66A passing on each side of the central fingers 86A and
86B and just inboard of adjacent lateral support fingers 88A, 88B.
When the upper surface of the end effector 66A reaches the height
of the pads 94 at the tip of the fingers, the pads 94 will engage
the underside of the substrate 126 causing the shuttle 70 to
acquire the substrate 126 from the end effector 66A. When the end
effector 66A reaches the position shown in FIG. 7B, it may be
withdrawn from the load lock chamber 50 via horizontal translation.
Once the end effector 66A is withdrawn, the valve 60 may be closed
and the chamber 50 pumped down.
The platen 120 may then be raised from its initial height in FIG.
7A to a raised height shown in FIG. 7C. During movement between the
initial height and the raised height, the platen 120 passes around
the fingers of the shuttle, each finger being accommodated by an
associated one of the channels 124 (see FIGS. 7D and 7E). When the
upper surface of the platen 120 contacts the underside of the
substrate 126, it raises the substrate 126 off of the fingers (more
particularly, pads 94) to acquire the substrate 126 from the
shuttle 70. With the substrate 126 held by the platen 120 as shown
in FIG. 7C, the substrate 126 may be heated or otherwise prepared
to ready it for processing.
A multiple substrate cassette (not shown) may also be employed in
the load lock chambers 50 or 52. By repeating the above procedure
for each substrate in a multiple substrate cassette, the load lock
chamber 50 may be used as a buffer for storage of substrates prior
to processing. More details of a multiple substrate cassette are
provided in above-mentioned U.S. patent application for an "In-Situ
Substrate Transfer Shuttle," U.S. Ser. No. 09/082,488, filed on May
20, 1998, and incorporated by reference above.
Once the substrate 126 is heated, the platen 120 may be lowered and
returned to the position of FIG. 7B, with the shuttle 70
reacquiring the substrate 126 from the platen 120 in the
process.
With a substrate 126 supported on the shuttle 70 in the load lock
chamber 50, after any heating of the substrate 126 and pump down of
the load lock chamber 50 and of the first processing chamber 54A,
the valve 56A may be opened to establish communication between the
load lock chamber 50 and the processing chamber 54A. With the
shuttle in this initial position, the pinion gears of the drive
mechanism 100 of the load lock 50 are engaged to the racks of the
shuttle 70 adjacent the downstream ends of the shuttle's rails. To
move the substrate into the processing chamber, the motor of the
drive mechanism may be powered so as to move the shuttle downstream
through the valve 56A and into the first processing chamber. When
the shuttle reaches a target position in the first processing
chamber 54A, its movement is stopped, leaving the shuttle and
substrate in the target position.
As shown in FIGS. 8A-8B, each processing chamber includes a
susceptor 130 for supporting a substrate 126 during processing. The
plan area of the susceptor 130 is slightly larger than that of the
substrate 126 and the susceptor 130 has an upper surface 132
configured to contact substantially the entire underside of the
substrate 126 during processing. The upper surface 132 of the
susceptor 130 is continuous except for interruptions caused by the
presence of passages for the lift pins 134 which may extend through
the susceptor 130 from below. As illustrated, the susceptor 130 has
a central pedestal 136 which may be raised and lowered to raise and
lower the susceptor 130. The lift pins 134 are secured at their
lower ends to a pin plate 138. The pins and pin plate are generally
raised and lowered by an outer shaft 139 which surrounds the
central pedestal 136. In one embodiment, lift pins 134 and pin
plate 138 move independently from susceptor 130. Lift pins 134
support a substrate when they are in an extended position. As the
lift pins are retracted, the substrate is lowered onto the
susceptor 130. When susceptor 130 is caused to rise, the lift pins
are caused to retract to a position below the surface 132 of the
susceptor 130. The pins may pass below surface 132 by virtue of a
counterbore located within surface 132.
This embodiment allows a convenient way of transferring support of
the substrate from the pins 134 to the susceptor 130 as the
susceptor 130 is raised. More details of this pin system may be
found in U.S. patent application Ser. No. 08/950,277, entitled "A
Vacuum Processing System Having Improved Substrate Heating and
Cooling", filed Oct. 14, 1997, assigned to the assignee of the
present invention and incorporated herein by reference.
In the illustrated embodiment, each chamber includes six lift pins
134 arranged in pairs extending from upstream to downstream in the
chamber. Like the support fingers and for the same reasons, the
lift pins 134 may also be advantageously located at about 15-30% of
the dimension of the substrate 126 and more preferably about 22% of
the width of the substrate 126. They may even more preferably be
located just inside of the distal end of the pad 94 location. While
it would be preferable to have both the pins 134 and the pads 94 at
the 22% point, such placement would not allow the same to pass
around each other. Thus, it may be advantageous to have the pins
and pads close to each other, but to have the pins just nearer to
the centerline of the substrate that the pads. In this way,
relative movement can be accomplished without contact.
The lift pins 134 may have the general cross-sectional shape of a
"T". A corresponding counterbore, as mentioned above, may be placed
in the susceptor 130 around the lift pin holes so that the lift
pins, when fully retracted, are below the level of the top surface
132 of the susceptor 130. The substrate then does not contact the
lift pins in their retracted positions. In this way, the lift pins
have a minimal thermal signature. In other words, the lift pins
134, and their passages through the susceptor 130, do not
significantly affect the even distribution of temperature across
the susceptor 130 and thus across the substrate 126. Thus, the high
process requirements with regard to uniformity of temperature for,
e.g., TFT formation may be advantageously achieved.
When the shuttle 70 carrying the substrate 126 enters the
processing chamber 54A, the substrate 126 and shuttle fingers 86A,
86B, 88A, and 88B pass over the susceptor 130 which is at a first
height as shown in FIG. 8A. The lift pins 134 may be in an extended
position relative to the susceptor 130 (as shown in FIGS. 8A and
8B) or may be in a retracted position. When the substrate 126 and
shuttle 70 are stopped in a target position immediately above the
susceptor 130, the susceptor 130 and/or lift pins 134 are raised.
As lift pin plate 138, lift pins 134, and/or the susceptor 130 are
raised, the pins (stationary and in the extended position) contact
the underside of the substrate 126 (FIG. 8A) and raise the
substrate 126 out of the engagement with the shuttle 70 (FIG. 8B).
With the substrate 126 in this intermediate position, the shuttle
70 may be withdrawn from the processing chamber 54A, with the
fingers 86A, 86B, 88A, and 88B passing around the lift pins 134 and
between the substrate 126 and the susceptor 130, at least one of
the cross members 80A, 80B of the shuttle 70 passing over the
substrate 126. The shuttle 70 may be withdrawn to the load lock
chamber 50 or may be driven into the second processing chamber 54B
or therebeyond, e.g., to service other substrates by transporting
the same to other chambers, etc. Once, however, the shuttle 70 is
out of the chamber 54A, the chamber 54A may be sealed by shutting
the valve 56A (and valves 58A and 56B if these have been opened).
The pins 134 may then be lowered relative to the susceptor 130 to
place the substrate atop the susceptor 130.
At this point, processing may begin. When processing is complete
and any process gases evacuated (if necessary), the valve 56A may
be opened, establishing communication between the load lock chamber
50 and the processing chamber 54A. Of course, valves 58A and 56B
may also be opened if the shuttle has been sent downstream. The
lift pins 134 and pin plate 138 may then be raised, thus raising
the substrate above the susceptor 130 such that the substrate is
supported on the lift pins. The shuttle 70 is returned to the
processing chamber 54A in a similar fashion as when delivering the
substrate 126 to the processing chamber 54A. As the shuttle
approaches a target position, the fingers 86A, 86B, 88A, and 88B
pass between the substrate 126 and the susceptor 130, passing
around the lift pins 134. The cross-member 80A passes over the
substrate 126. When the shuttle 70 reaches the target position, the
susceptor 130 and/or pins 134 may be lowered to the position of
FIG. 8A, during which the fingers 86A, 86B, 88A, and 88B acquire
the substrate 126 from the pins 134.
Next, the substrate 126 may be delivered to the second processing
chamber 54B through valves 58A and 56B. The steps of this transfer
may be similar to the steps involved in the transfer from the load
lock chamber 50 to the first processing chamber 54A. Via a similar
process, the substrate 126 may be transferred to the third
processing chamber 54C. This may be done with either of the
shuttles 70 and 72. Finally, the substrate may be withdrawn from
the third processing chamber 54C into the load lock chamber 52 by
the shuttle 72 via a reverse of steps similar to those performed
with the shuttle 70 in transferring the substrate from the load
lock chamber 50 to the first processing chamber 54A. Similarly, the
extraction of the substrate 126 from the cooling load lock chamber
52 by the robot end effector 68B may be performed by substantially
reversing the steps used with the robot end effector 66A in
introducing the substrate 126 to the heating load lock chamber
50.
The use of such lift pins 134 provides another advantage. In any of
the chambers, lift pins 134 may be used to elevate the substrate
126 above the heated or cooled susceptor 130. Such elevation may be
maintained for as long as necessary to bring the substrate
temperature to a desired level. For example, if the substrate 126
is to be cooled, but the susceptor 130 is at a high temperature,
maintaining the pins 134 in an elevated position may be useful for
cooling the substrate 126.
As shown in FIGS. 1 and 1A, alcoves or compartments 148 in the end
walls of the entrance and exit load locks are provided to
accommodate an associated end of a side rail of the shuttles 70 and
72, respectively. When the shuttle is in the target position in a
load lock chamber, the side rail's ends are received and
accommodated by such compartments. As noted above, the rails may be
generally longer than the length of process chambers 54A-54C. This
allows the volume of the load locks to be correspondingly
minimized. Such minimization is advantageous for, e.g.,
accomplishing a more convenient pump-down.
For a variety of reasons, it may be advantageous to attempt to
minimize chamber volume. Reduced chamber volume facilitates faster
and more economical pumping down of chambers, including reducing
the capacity requirements for any vacuum pumps. Additionally, the
introduction of process or inert gases is facilitated with a
reduced consumption of such gases. Heating and cooling may be more
easily facilitated. Process uniformity may be increased, for
example, by providing a more uniform plasma in the absence of voids
or cavities.
With respect to the process of chambers 54A-54C, an additional
benefit of providing each chamber with two valves 56A-56C, 58A-58C
is that this allows each such valve to be located substantially
adjacent the susceptor of the associated chamber. An even more
important benefit is that the drive mechanism 100 of each
processing chamber may be located in the outside of the cavity
defined by the valve housing. This significantly reduces
contamination of the chambers due to the drive mechanisms.
Advantageously, the system is configured so that certain components
may be serviced or replaced with minimal disruption of the system
or contamination of the system chambers. As illustrated in FIGS. 6A
and 6B, the drive motors 102 and encoders 110 may be serviced or
replaced from outside the island without risk of contamination. If
a drive shaft 104 or any of its associated components needs to be
serviced or replaced, such operation may be performed with the
valves on either side of the drive mechanism closed. Thus, the
interiors of the adjacent chambers will not become contaminated
from such action. Any contamination will be limited to the space
between the valves immediately surrounding the drive mechanism
which may be more readily cleaned than the interior of the adjacent
chambers.
A number of embodiments of the present invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, the particular processes
associated with fabricating a given device may advantageously be
associated with different chamber arrangements and sequences of
use. In this way, the types of chambers may be those employed in
etching processes, physical vapor deposition, chemical vapor
deposition, etc. In another modification, while three process
chambers have been described here, the system may employ a single
process chamber, two process chambers, or more than three process
chambers. The system of the present invention, as it is modular and
incremental, allows numerous modifications to suit any particular
process. For example, the shuttle of the present invention may be
controlled to even repeat processing steps for a particular
substrate if desired. In this way, the shuttle may be controlled to
be bidirectional. Accordingly, other embodiments are within the
scope of the following claims.
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